Through reducing incubation time,the low-level lactosed polyethyleneimine(L-PEI)was prepared by reductive amination of PEI with lactose.The content of galactose residue in the complex was determined with phenol-sulfuric acid method and the lactose rate was calculated.The result shows that:a good linear relationship within galactose concentration range of 1.25～12.5μg/mL(r=0.996),RSD of reappearance was 2.16%,the average rate of recoveries was 92.5%(RSD=2.18%).With a 6.27% lactose rate,the developed L-PEI reached its expected level.
